Diagnostic responsibility beyond the implant site

The integration of cone beam computed tomography (CBCT) has become the standard of care in implantology for the three-dimensional evaluation of maxillofacial structures. However, this technology presents the practitioner with a clinical and ethical challenge: the management of incidental findings located outside the primary area of interest. While identifying these anomalies can improve overall patient care, it imposes a diagnostic responsibility on the clinician for the entire acquired volume, at the risk of missing a pathology or, conversely, generating unnecessary additional examinations due to a lack of knowledge regarding anatomical variants.

This retrospective study, analyzing 368 consecutive CBCT examinations performed for implant planning at the University of Alberta, aims to determine the prevalence and anatomical distribution of incidental findings (IF) and so-called "actionable" findings (AF). The latter are specifically defined as anomalies requiring follow-up, referral to a specialist, or active management according to the recommendations of an oral and maxillofacial radiologist.

The objective is to map these findings across four anatomical zones and evaluate their correlations with demographic data (age, sex) and exposure parameters, notably the field of view (FOV). The authors test the hypothesis of a high prevalence of these findings in patients candidates for implantology, while seeking to identify whether age or the extent of the imaged volume significantly influence the detection of clinically relevant anomalies.

Methodology

This retrospective cross-sectional observational study was conducted on a series of consecutive CBCT scans (n = 368) performed specifically for dental implant planning within a university imaging center. Only examinations accompanied by a complete radiological report interpreted by an oral and maxillofacial radiologist (OMR) were included.

The evaluation protocol was based on a structured analysis divided into four distinct anatomical zones:

• Zone 1: Skull and paranasal sinuses.
• Zone 2: Zygomatico-maxillary/orbital complex and temporomandibular joint (TMJ).
• Zone 3: Maxillo-mandibular region.
• Zone 4: Structures located under the mandible.

The results were classified into two categories: incidental findings (IF), defined as observations unrelated to the implant site and requiring no further management, and actionable findings (AF), requiring additional evaluation, follow-up, or management according to OMR recommendations. Statistical analyses, including univariate and multivariate methods, were used to evaluate associations between the prevalence of IF/AF and parameters such as field of view (FOV), age, and sex.

Global prevalence of incidental and actionable findings

Of the 368 CBCT examinations analyzed for implant planning, the study reveals a high prevalence of incidental findings (IF) and findings requiring clinical action (AF). IFs were identified in 257 patients (69.8%), while AFs, defined by the need for follow-up, referral, or management according to radiological recommendations, concern 54.1% of the cohort (n=199).

Demographic and statistical correlations

Analysis shows that the prevalence of IF increases significantly with age, rising from 50% in patients aged ≤40 years to 78.8% in patients aged >70 years. Gender is also an influencing factor: men show a higher prevalence of IF than women (76.2% vs. 64.5%; p = 0.01).

Regarding AF, the results are more nuanced:

• In univariate analysis, no significant association was found with sex (p = 0.97) or age (p = 0.25).
• However, multivariate analysis suggests higher probabilities of AF in patients >70 years old, although the overall model is not statistically significant.
• Anomalies of Zone 2 (zygomatico-maxillary/orbital complex and TMJ) are significantly more frequent in women (21.5%) than in men (7.1%; p < 0.001).

Anatomical distribution and imaging parameters

Findings are distributed across several anatomical areas, with the maxillary sinus being the most frequent location. The field of view (FOV) influences the detection of IFs, but not that of AFs (p = 0.94).

Finally, IFs are more frequent in medium FOV scans (72.2%), highlighting the importance of a systematic reading of the entire volume, regardless of the primary implant area of interest.

Clinical analysis of incidental findings on CBCT

The results of this retrospective study conducted on 368 patients highlight a major clinical reality for the implantologist: more than one in two patients (54.1%) present findings qualified as actionable (AF), requiring further evaluation, follow-up, or referral to a specialist. This high prevalence confirms that pre-implant CBCT cannot be limited to the edentulous area alone. Incidental findings (IF) are particularly frequent in men (76.2%) and increase linearly with age, rising from 50% in those under 40 to 78.8% in those over 70. The most critical sites include the maxillary sinus (35.1%) and the cervical spine (27.4%), underscoring the importance of a careful reading of peripheral areas.

Methodologically, the study shows that while IFs are more frequent in medium fields of view (FOV), the prevalence of actionable findings (AF) does not vary significantly according to the FOV (p = 0.94). This means that even a restricted volume can contain clinically relevant information requiring intervention. However, the study's limitations must be noted: it is a monocentric work in an academic setting, whose results on AFs are based on the recommendations of oral and maxillofacial radiologists (OMR) and not on confirmed clinical outcomes. Nevertheless, the practical implication is direct: the practitioner's ethical and legal responsibility involves the interpretation of the entire radiographed volume, regardless of the initial objective of the examination.

Summary of results

This retrospective study of 368 scans reveals that 69.8% of CBCTs performed for implant planning show incidental findings, of which 54.1% are considered actionable (requiring follow-up or intervention). These anomalies are mainly concentrated in the maxillary sinus (35.1%) and the cervical spine (27.4%), with a prevalence that rises from 50% in those under 40 to 78.8% in those over 70.

In concrete terms, for the practitioner:

• Examine the entire volume: More than one in two patients requires management or a specialist opinion for a pathology unrelated to the implant site (sinusitis, vascular calcifications, TMJ).
• Do not rely on the FOV size: Contrary to popular belief, the frequency of actionable findings does not decrease with a reduced field of view; every acquisition requires an exhaustive analysis.
• Protect your liability: Your legal obligation covers the entire radiographed volume. In case of doubt regarding anatomical structures outside your field of expertise, systematically delegate the interpretation to an oral and maxillofacial radiologist.

Technical lexicon of the study

Incidental Findings (IF): Incidental findings identified on the CBCT, unrelated to the initial implant planning site and requiring no additional management recommendations.

Actionable Findings (AF): Radiographic abnormalities deemed clinically significant by the radiologist (OMR), requiring further evaluation, follow-up, or referral to another specialist.

CBCT (Cone-Beam Computed Tomography): Cone-beam three-dimensional imaging system allowing precise multi-planar analysis of maxillofacial structures for guided implant surgery.

Field of View (FOV): Field of vision or acquisition volume of the radiographic examination; the study shows that its size influences the prevalence of incidental findings (IF) but not that of AF.

OMR (Oral and Maxillofacial Radiologist): Specialist in oral and maxillofacial radiology whose systematic interpretation and recommendations constitute the gold standard for the classification of AF in this study.

Zygomaticomaxillary complex: Anatomical area including the zygomaticomaxillary complex, the orbit and the temporomandibular joint (TMJ), identified as Zone 2 in the structured assessment protocol.

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